Corrects spelling error on Activities page

Related Issue

Fixes #

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[ ] I linked an issue in the previous section
[ ] I have commented on the linked issue
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[x] I have tested the change to the best of my ability against the sandbox or a local build.

Optional items:

[ ] My change adds new text and requires a change to translations.
[ ] My change requires a change to the documentation.
[ ] I have submitted a PR to the documentation repo.
[ ] I was not able to test... (explain below, e.g. you did not have permissions to test a specific feature)
[ ] This change depends O-FISH Realm repository changes (explain below)
Optional: Add any explanations here It might be that this change should have been an i18N string to start with, but this is a simple fix on the spelling, that was not a i18N string to start with.
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